1. Technical Field
The present invention relates to methods for making polycyclic polymers that contain pendant anhydride groups. More specifically the invention relates to methods of polymerizing polycycloolefins having pendant anhydride groups alone or in combination with other polycycloolefin monomers in the presence of a nickel containing single component catalyst system.
2. Background
Copolymers polymerized from polycycloolefin monomers and maleic anhydride monomers are disclosed in International Patent Application Publication No. WO 97/33198 to The B.F.Goodrich Company. In one disclosed embodiment, a polycycloolefin containing a pendant acid labile group is copolymerized with maleic anhydride via a free radical process to yield a polymer product wherein the maleic anhydride becomes incorporated directly into the backbone of the polymer generally represented as follows: 
In European Patent Application Publication No. EP 0 794 458 to Lucent Technologies Inc. there is disclosed a copolymer polymerized from a polycycloolefin, maleic anhydride, and an acrylate or methacrylate monomer containing an acid labile group. These monomers are also polymerized via a free radical process to yield a polymer product of the general structure: 
When polymerized via free radical processes the polycycloolefin and maleic anhydride monomers of the foregoing disclosures incorporate into the polymer backbone in a one-to-one ratio yielding an alternating copolymer. There is no disclosure of a polymerization process for preparing random copolymers of polycycloolefins that contain pendant anhydride moieties. In addition to limitations in backbone architecture, free radical polymerization of functional group containing polycycloolefins generally produces polymers of lower molecular weights and in lower yields.
It is an object of the invention to provide a more efficient process for preparing novel polycyclic polymer compositions comprising repeating units containing a pendant cyclic anhydride group.
It is another object of the invention to provide polycyclic copolymer compositions containing repeating units having pendant cyclic anhydride groups in combination with one or more polycyclic repeating units having a pendant sulfonamide, hydrocarbyl, and functional groups.
It is still another object of the invention to provide a polycyclic copolymer composition containing repeating units having a pendant cyclic anhydride group and a pendant acid labile group.
It is a further object of the invention to provide a polycyclic copolymer composition containing repeating units having a pendant cyclic anhydride group and a pendant hydrocarbyl group.
It is another object of the invention to provide a polycyclic copolymer composition containing repeating units having a pendant cyclic anhydride group, a pendant acid labile group, and a pendant sulfonamide group.
The polymers of this invention are prepared by polymerizing a polycyclic monomer having the respective pendant moieties in the presence of a nickel addition catalyst.
The polycyclic polymers of the present invention comprise repeating units polymerized from at least one polycycloolefin monomer wherein at least a portion of which contain a pendant anhydride group. As stated herein the terms xe2x80x9cpolycycloolefin,xe2x80x9d xe2x80x9cpolycyclic,xe2x80x9d and xe2x80x9cnorbornene-typexe2x80x9d monomer are used interchangeably and mean that the monomer contains at least one norbornene moiety as shown below: 
In the formula above, x represents oxygen, nitrogen, sulfur or a methylene group of the formula xe2x80x94(CH2)nxe2x80x2xe2x80x94 wherein nxe2x80x2 is an integer of 1 to 5.
The simplest polycyclic monomer of the invention is the bicyclic monomer, bicyclo[2.2.1]hept-2-ene, commonly referred to as norbornene. The term norbornene-type monomer is meant to include norbornene, substituted norbornene(s), and any substituted and unsubstituted higher cyclic derivatives thereof so long as the monomer contains at least one norbornene or substituted norbornene moiety. The substituted norbornenes and higher cyclic derivatives thereof contain a pendant hydrocarbyl substituent(s) or a pendant functional substituent(s) containing a heteroatom such as oxygen or nitrogen.
The anhydride functional norbornene-type monomers are represented by the structure below: 
wherein x independently represents oxygen, nitrogen, sulfur or a methylene group of the formula xe2x80x94(CH2)nxe2x80x2xe2x80x94; nxe2x80x2 is an integer of 1 to 5, preferably 1 or 2, and more preferably 1; m is an integer from 0 to 5, preferably 0 or 1; and R1 and R4 independently represent hydrogen, linear or branched linear and branched C1-C20 alkyl; R2 and R3 independently represent hydrogen, and linear and branched C1-C20 alkyl, with the proviso that at least one of R2 and R3 is a pendant cyclic anhydride group 
or at least one of R1 and R2 or R3 and R4 can be taken together with the ring carbon atom to which they are attached to form a spirally attached cyclic anhydride group. Monomers containing the spirally attached anhydride group can be represented by the formula: 
wherein R3, R4, x and m are as defined above.
The norbornene-type monomers of Formula I can be copolymerized with norbornene-type monomers containing pendant sulfonamide functional groups, norbornene-type monomers containing pendant hydrocarbyl and/or functional groups, and mixtures of the foregoing monomers.
The norbornene-type monomers containing pendant sulfonamide groups can be represented by Formula II below: 
wherein x and m are as defined above and R5 and R8 independently represent hydrogen, linear or branched linear and branched C1-C20 alkyl; R6 and R7 independently represent hydrogen, linear and branched C1-C20 alkyl or a sulfonamide group, with the proviso that at least one of R2 and R3 is a pendant sulfonamide group of the formulae:
xe2x80x83xe2x80x94Axe2x80x94NRxe2x80x2SO2Rxe2x80x3 and xe2x80x94Axe2x80x94SO2NRxe2x80x2Rxe2x80x2xe2x80x3
or a cyclic sulfonamide group formed by combining R6 and R7 together with the two ring carbon atoms to which they are attached to form a heterocyclic ring of the formula: 
wherein mxe2x80x2 is an integer from 1 to 3. Monomers containing the foregoing group can be represented by Formula IIa below: 
In Formula IIa R5, R8, x, m, and mxe2x80x2 are as defined previously. In Formula IIa R5 and, R8 are preferably hydrogen.
In the formulae above xe2x80x94Axe2x80x94 is a divalent radical selected from xe2x80x94(CR1xe2x80x2R2xe2x80x2)nxe2x80x2xe2x80x94, xe2x80x94(CHR1xe2x80x2)nxe2x80x3O(CHR1xe2x80x2) nxe2x80x3xe2x80x94, xe2x80x94(CHR1xe2x80x2)nxe2x80x3C(O)O(CHR1xe2x80x2)nxe2x80x3xe2x80x94, xe2x80x94(CHR1xe2x80x2)nxe2x80x3C(O)(CHR1xe2x80x2)nxe2x80x3xe2x80x94, C3-C8 cycloalkyl, C6-C14 aryl, cyclic ethers and cyclic diethers containing 4 to 8 carbon atoms, wherein nxe2x80x2 independently represents an integer from 0 to 10, nxe2x80x3 represents an integer from 1 to 10, and R1xe2x80x2 and R2xe2x80x2 independently represent hydrogen, linear and branched C1-C10 alkyl and halogen, preferably chlorine and fluorine. Divalent radical xe2x80x94Axe2x80x94 represents the group xe2x80x94(CHR1xe2x80x2)nxe2x80x3OC(O)xe2x80x94 only when the sulfonamide group is xe2x80x94NRxe2x80x2SO2Rxe2x80x3.
The divalent cycloalkyl radicals include substituted and unsubstituted C3 to C8 cycloalkyl moieties represented by the formula: 
wherein xe2x80x9caxe2x80x9d is an integer from 2 to 7 and Rq when present represents linear and branched C1-C10 alkyl groups, linear and branched C1-C10 haloalkyl, and halogen, preferably chlorine and fluorine. As used here and throughout the specification the term haloalkyl means that at least one hydrogen atom on the alkyl radical is replaced by a halogen. The degree of halogenation can range from at least one hydrogen atom being replaced by a halogen atom (e.g., a monofluoromethyl group) to full halogenation (perhalogenation) wherein all hydrogen atoms on the alkyl group have been replaced by a halogen atom (e.g., trifluoromethyl (perfluoromethyl)). Preferred divalent cycloalkylene radicals include cyclopentylene and cyclohexylene moieties represented by the following structures: 
wherein Rq is defined above. As illustrated here and throughout this specification, it is to be understood that the bond lines projecting from the cyclic structures and/or formulae represent the divalent nature of the moiety and indicate the points at which the carbocyclic atoms are bonded to the adjacent molecular moieties defined in the respective formulae. As is conventional in the art, the diagonal bond line projecting from the center of the cyclic structure indicates that the bond is optionally connected to any one of the carbocyclic atoms in the ring. It is also to be understood that the carbocyclic atom to which the bond line is connected will accommodate one less hydrogen atom to satisfy the valence requirement of carbon.
The divalent aryl radicals include substituted and unsubstituted aryl moieties. A representative divalent aryl moiety is shown below. 
wherein Rq is as defined above. In the above formulae R1xe2x80x2 and R2xe2x80x2 independently represent linear and branched C1-C10 alkyl, linear and branched C1-C10 haloalkyl, and halogen selected from chlorine, bromine, fluorine, and iodine, preferably fluorine.
The divalent cyclic ethers and diethers can be represented by the formulae: 
Rxe2x80x2 represents hydrogen, linear and branched tri(C1-C10) alkylsilyl, xe2x80x94C(O)CF3, and xe2x80x94C(O)OR, and xe2x80x94OC(O)OR, wherein R is linear and branched C1-C10 alkyl, preferably t-butyl, linear and branched C1-C10 haloalkyl, substituted and unsubstituted C6-C14 aryl, and substituted and unsubstituted C7-C20 aralkyl. As used here and throughout the specification the term substituted cycloalkyl, aryl (e.g., phenyl), and aralkyl means that the respective rings can contain monosubstitution or multisubstitution and the substituents are independently selected from linear and branched C1-C5 alkyl, linear and branched C1-C5 haloalkyl, substituted and unsubstituted phenyl, and halogen, preferably, chlorine and fluorine.
Rxe2x80x3 represents linear and branched C1-C10 alkyl, linear and branched C1-C10 haloalkyl, xe2x80x94C(O)OR, xe2x80x94(CHR1xe2x80x2) nxe2x80x3xe2x80x94OR, xe2x80x94(CHR1xe2x80x2)nxe2x80x3xe2x80x94C(O)R, substituted and unsubstituted C3 to C8 cycloalkyl(as defined above), cyclic esters (lactones) containing 2 to 8 carbon atoms (excluding the carbonyl carbon), cyclic ketones containing 4 to 8 carbon atoms (excluding the carbonyl carbon), cyclic ethers and cyclic diethers containing 4 to 8 carbon atoms, wherein R, R1xe2x80x2, and nxe2x80x3 are as defined above.
Rxe2x80x2xe2x80x3 represents hydrogen, linear and branched C1-C10 alkyl, linear and branched C1-C10 haloalkyl, xe2x80x94C(O)OR, xe2x80x94(CHR1xe2x80x2)nxe2x80x3xe2x80x94OR, xe2x80x94(CHR1xe2x80x2)nxe2x80x3xe2x80x94C(O)R, substituted and unsubstituted C3 to C8 cycloalkyl (as defined above), cyclic esters (lactones) containing 2 to 8 carbon atoms (excluding the carbonyl carbon), cyclic ketones containing 4 to 8 carbon atoms (excluding the carbonyl carbon), cyclic ethers and cyclic diethers containing 4 to 8 carbon atoms, wherein R, R1xe2x80x2, and nxe2x80x3 are as defined above.
The norbornene-type monomers containing pendant functional groups can be represented by Formula III below: 
wherein x, m, are as previously defined and R9 to R12 independently represent a radical selected from xe2x80x94(CH2)nxe2x80x94C(O)OR13, xe2x80x94(CH2)nxe2x80x94OR13, xe2x80x94(CH2)nxe2x80x94OC(O)R13, xe2x80x94(CH2)nxe2x80x94C(O)R13, xe2x80x94(CH2)nxe2x80x94OC(O)OR13, and xe2x80x94(CH2)nxe2x80x94C(O)OR14, wherein n independently represents an integer from 0 to 10; R13 independently represents hydrogen, linear and branched C1-C10 alkyl, linear and branched C1-C10 haloalkyl, linear and branched C2-C10 alkenyl, linear and branched C2-C10 alkynyl, C5-C12 cycloalkyl, C6-C14 aryl, and C7-C24 aralkyl; R14 represents an acid labile moiety selected from xe2x80x94C(CH3)3, xe2x80x94Si(CH3)3, xe2x80x94CH(R15)OCH2CH3, xe2x80x94CH(R15)OC(CH3)3 or the following cyclic groups: 
wherein R15 represents hydrogen or a linear and branched C1-C5 alkyl group. The alkyl groups include methyl, ethyl, propyl, i-propyl, butyl, i-butyl, t-butyl, pentyl, t-pentyl and neopentyl. In the above structures, the single bond line projecting from the cyclic groups indicates the position where the cyclic protecting group is bonded to the acid substituent. Examples of R14 radicals include 1-methyl-1-cyclohexyl, isobomyl, 2-methyl-2-isobomyl, 2-methyl-2-adamantyl, tetrahydrofuranyl, tetrahydropyranoyl, 3-oxocyclohexanonyl, mevalonic lactonyl, 1-ethoxyethyl, and 1-t-butoxyethyl.
The R14 radical can also represent dicyclopropylmethyl (Dcpm), and dimethylcyclopropylmethyl (Dmcp) groups which are represented by the following structures: 
In Formula II above, preferably at least one of R5 to R8 is selected from the radical xe2x80x94(CH2)nxe2x80x94C(O)OR14 wherein n and R14 are as previously defined.
The norbornene-type monomers containing pendant hydrocarbyl groups can be represented by Formula IV below: 
wherein x and m are as previously defined and R16 to R19 independently represent hydrogen, linear and branched C1-C10 alkyl, linear and branched C1-C10 haloalkyl, linear and branched, C2-C10 alkenyl, linear and branched C2-C10 alkynyl, C5-C12 cycloalkyl, C6-C12 aryl, and C7-C24 aralkyl. R16 and R19 together with the two ring carbon atoms to which they are attached can represent a cycloaliphatic group containing 4 to 12 carbon atoms or an aryl group containing 6 to 14 carbon atoms. The cycloalkyl, cycloaliphatic ,aryl, and aryl groups set forth above can optionally be substituted with linear and branched C1-C5 alkyl, linear and branched C1-C5 haloalkyl, C5-C12 cycloalkyl, C6-C12 aryl, and halogen, preferably chlorine and fluorine.
Other monomers that can be copolymerized with the norbornene-type monomers of Formulae I, II, III, and IV are maleic anhydride, SO2, CO, and acrylate and methacrylate monomers. Preferred acrylate and methacrylate monomers are represented by the formulae CH2xe2x95x90CHR20C(O)OR13, and CH2xe2x95x90CHR20C(O)OR14 wherein R20 is hydrogen or methyl and R13 and R14 are as defined above. Accordingly, the polymers of the invention comprise repeating units polymerized from at least one monomer(s) of Formula I in optional combination with a monomer(s) selected from Formula II, Formula III, Formula IV, maleic anhydride, SO2, CO, acrylate methacrylate monomers, and combinations thereof.
The addition polymers of the present invention can be prepared via standard free radical solution polymerization methods that are well-known by those skilled in the art. Typical free radical initiators are peroxygen compounds azo compounds and persulfates. Free radical initiators include, for example, benzoyl peroxide, t-butyl diperphthalate, perargouyl peroxide, 1-hydroxycyclohexyl hydroperoxide, dialkylperoxides, diacylperoxides, azodiisobutyronitrile, and dimethylazodiisobutyronitrile. Suitable solvents include alkanes such as pentane, hexane, octane, nonane, and decane, cycloalkanes such as cyclohexane, cycloheptane, cyclooctane, decalin, and norbornane, aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, and cumene, halogenated hydrocarbons such as chlorobutane, bromohexane, dichloroethane, and chlorobenzene, and organic solvents such as ethyl acetate, n-butyl acetate, isobutyl acetate, methylproionate, and THF. Free radical polymerization techniques are set forth in the Encyclopedia of Polymer Science, John Wiley and Sons, 13, 708 (1988). When copolymerizing maleic anhydride, SO2, and CO into the polymer backbone free radical polymerization is the preferred route.
Alternatively, and preferably, the polycyclic monomers of this invention are addition polymerized in the presence of a catalyst represented by the formula:
EnNi(C6F5)2
wherein n is 1 or 2 and E represents a neutral electron donor ligand. When n is 1, E preferably is a xcfx80-arene ligand preferably selected from toluene, benzene, and mesitylene. When n is 2, E preferably is selected from diethylether, tetrahydrofuran (THF), and dioxane. The ratio of monomer to catalyst (based on nickel) in the reaction medium preferably ranges from about 2000:1 to about 50:1. The reaction can be run in a hydrocarbon solvent. Preferred solvents include cyclohexane, and toluene. The reaction can be run at a temperature range of from about 0xc2x0C. to about 70xc2x0 C., preferably from about 10xc2x0C. to about 50xc2x0 C., and more preferably from about 20xc2x0 C. to about 40xc2x0 C. Preferred catalysts of the above formula include (toluene)bis(perfluorophenyl) nickel, (mesitylene)bis(perfluorophenyl) nickel, (benzene)bis(perfluorophenyl) nickel, bis(tetrahydrofuran)bis(perfluorophenyl) nickel, and bis(dioxane)bis(perfluorophenyl) nickel.
The norbornene-type monomers of Formula I, II, III and IV can alternatively be polymerized via ring-opening metathesis polymerization (ROMP). The ROMP polymers of the present invention are polymerized in the presence of a metathesis ring-opening polymerization catalyst in an appropriate solvent. Methods of polymerizing via ROMP and the subsequent hydrogenation of the ring-opened polymers so obtained are disclosed in U.S. Pat. Nos. 5,053,471 and 5,202,388 which are incorporated herein by reference.
In one ROMP embodiment the polycyclic monomers of the invention can be polymerized in the presence of a single component ruthenium or osmium metal carbene complex catalyst such as those disclosed in WO 95-US9655. The monomer to catalyst ratio employed should range from about 100:1 to about 2,000:1, with a preferred ratio of about 500:1 (based on ruthenium or osmium metal). The reaction can be conducted in halohydrocarbon solvent such as dichloroethane, dichloromethane, chlorobenzene and the like or in a hydrocarbon solvent such as toluene. The amount of solvent employed in the reaction medium should be sufficient to achieve a solids content of about 5 to about 40 weight percent, with 6 to 25 weight percent solids to solvent being preferred. The reaction can be conducted at a temperature ranging from about 0xc2x0C. to about 60xc2x0 C., with about 20xc2x0 C. to 50xc2x0 C. being preferred.
A preferred metal carbene catalyst is bis(tricyclohexylphosphine)benzylidene ruthenium. Surprisingly and advantageously, it has been found that this catalyst can be utilized as the initial ROMP reaction catalyst and as an efficient hydrogenation catalyst to afford an essentially saturated ROMP polymer. No additional hydrogenation catalyst need be employed. Following the initial ROMP reaction, all that is needed to effect the hydrogenation of the polymer backbone is to maintain hydrogen pressure over the reaction medium at a temperature above about 100xc2x0 C. but lower than about 220xc2x0 C., preferably between about 150xc2x0 C. to about 200xc2x0 C.
The addition polymers of the invention comprise repeating units of the formula: 
wherein x independently represents oxygen, nitrogen, sulfur or a methylene group of the formula xe2x80x94(CH2)nxe2x80x2xe2x80x94; nxe2x80x2 is an integer of 1 to 5, preferably 1 or 2, and more preferably 1; n is an integer from 0 to 5; and R1 and R4 independently represent hydrogen, linear or branched linear and branched C1-C20 alkyl; R2 and R3 independently represent hydrogen, and linear and branched C1-C20 alkyl, with the proviso that at least one of R2 and R3 is a pendant cyclic anhydride group of the formula: 
or at least one of R1 and R2 or R3 and R4 is be taken together with the ring carbon atom to which they are attached to form a spirally bonded cyclic anhydride group. Preferred repeating units under Formula Ib are represented below: 
wherein x, m and nxe2x80x2 are as previously defined.
In another embodiment of the invention the polymer comprises repeating units of Formula Ib and repeating units of Formula IIIa below: 
wherein R9 to R12, x, and m are as defined previously. Preferred repeating units of lila are selected from one or more of the repeating unit structures under Formulae IIIb and IIIc below: 
wherein x, and m are as previously defined, nxe2x80x2 is and integer from 0 to 10, and R13 and R14 are as defined previously.
Repeating units containing pendant sulfomamide groups are represented by Formula IIa below: 
wherein x, m, and R5 to R8 are as previously defined.
Repeating units containing pendant hydrocarbyl groups are represented as Formula VIa as follows: 
wherein x, m, and R16 to R19 are as previously defined.
Polymers comprising repeating units of Formula Ib and IIIc are useful in photoresist applications. These polymers can further comprise repeating units selected from Formulae II, III, IV, maleic anhydride, SO2, CO, and combinations thereof.
The ROMP hydrogenated polymers of the invention comprise repeating units of the formula: 
wherein x, m, and R1 to R4 are as defined previously. A ROMP polymer contains a repeating unit with one less cyclic unit than did the starting monomer. Accordingly, the repeating units derived from the monomers set forth under Formulae II, III and IV will have similar ring opened repeating unit structures as in Formula Ic above.
The photoresist compositions of the present invention comprise the disclosed polycyclic compositions, a solvent, and an photosensitive acid generator (photoinitiator). Optionally, a dissolution inhibitor can be added in an amount of up to about 20 weight % of the composition. A suitable dissolution inhibitor is t-butyl cholate (J.V. Crivello et al., Chemically Amplified Electron-Beam Photoresists, Chem. Mater., 1996, 8, 376-381).
Upon exposure to radiation, the radiation sensitive acid generator generates a strong acid. Suitable photoinitiators include triflates (e.g., triphenylsulfonium triflate), pyrogallol (e.g., trimesylate of pyrogallol); onium salts such as triarylsulfonium and diaryliodium hexafluoroantimonates, hexafluoroarsenates, trifluoromethanesulfonates; esters of hydroxyimides, -bis-sulfonyl-diazomethanes, sulfonate esters of nitro-substituted benzyl alcohols and napthoquinone-4-diazides. Other suitable photoacid initiators are disclosed in Reichmanis et al., Chem. Mater. 3, 395, (1991). Compositions containing triarylsulfonium or diaryliodonium salts are preferred because of their sensitivity to deep UV light (193 to 300 nm) and give very high resolution images. Most preferred are the unsubstituted and symmetrically or unsymmetrically substituted diaryliodium or triarylsulfonium salts. The photoacid initiator component comprises about 1 to 100 w/w % to polymer. The preferred concentration range is 5 to 50 w/w %.
The photoresist compositions of the present invention optionally contain a sensitizer capable of sensitizing the photoacid initiator to longer wave lengths ranging from mid UV to visible light. Depending on the intended application, such sensitizers include polycyclic aromatics such as pyrene and perlene. The sensitization of photoacid initiators is well-known and is described in U.S. Pat. Nos. 4,250,053; 4,371,605; and 4,491,628 which are all incorporated herein by reference. The invention is not limited to a specific class of sensitizer or photoacid initiator.
The present invention also relates to a process for generating a positive tone resist image on a substrate comprising the steps of: (a) coating a substrate with a film comprising the positive tone resist composition of the present invention; (b) imagewise exposing the film to radiation; and (c) developing the image.
The first step involves coating the substrate with a film comprising the positive tone resist composition dissolved in a suitable solvent. Suitable substrates are comprised of silicon, ceramics, polymer or the like. Suitable solvents include propylene glycol methyl ether acetate (PGMEA) cyclohexanone, butyrolactate, ethyl lactate, and the like. The film can be coated on the substrate using art known techniques such as spin or spray coating, or doctor blading. Preferably, before the film has been exposed to radiation, the film is heated to an elevated temperature of about 90xc2x0 C. to 150xc2x0 C. for a short period of time of about 1 min. In the second step of the process, the film is imagewise exposed to radiation suitably electron beam or electromagnetic preferably electromagnetic radiation such as ultraviolet or x-ray, preferably ultraviolet radiation suitably at a wave length of about 193 to 514 nm preferably about 193 nm to 248 nm. Suitable radiation sources include mercury, mercury/xenon, and xenon lamps, x-ray or e-beam. The radiation is absorbed by the radiation-sensitive acid generator to produce free acid in the exposed area. The free acid catalyzes the cleavage of the acid labile pendant group of the copolymer which converts the copolymer from dissolution inhibitor to dissolution enhancer thereby increasing the solubility of the exposed resist composition in an aqueous base. The exposed resist composition is readily soluble in aqueous base. This solubility is surprising and unexpected in light of the complex nature of the cycloaliphatic backbone and the high molecular weight of the norbornene monomer units bearing the carboxylic acid functionality. Preferably, after the film has been exposed to radiation, the film is again heated to an elevated temperature of about 90xc2x0 C. to 150xc2x0 C. for a short period of time of about 1 minute.
The third step involves development of the positive tone image with a suitable solvent. Suitable solvents include aqueous base preferably an aqueous base without metal ions such as tetramethyl ammonium hydroxide or choline. The composition of the present invention provides positive images with high contrast and straight walls. Uniquely, the dissolution property of the composition of the present invention can be varied by simply varying the composition of the copolymer.
The present invention also relates to an integrated circuit assembly such as an integrated circuit chip, multichip module, or circuit board made by the process of the present invention. The integrated circuit assembly comprises a circuit formed on a substrate by the steps of: (a) coating a substrate with a film comprising the positive tone resist composition of the present invention; (b) imagewise exposing the film to radiation; (c) developing the image to expose the substrate; and (d) forming the circuit in the developed film on the substrate by art known techniques.
After the substrate has been exposed, circuit patterns can be formed in the exposed areas by coating the substrate with a conductive material such as conductive metals by art known techniques such as evaporation, sputtering, plating, chemical vapor deposition, or laser induced deposition. The surface of the film can be milled to remove any excess conductive material. Dielectric materials may also be deposited by similar means during the process of making circuits. Inorganic ions such as boron, phosphorous, or arsenic can be implanted in the substrate in the process for making p or n doped circuit transistors. Other means for forming circuits are well known to those skilled in the art.